Motor clock provided with a spring automatically wound



April 26, 1960 SHIRO SONOBE ETAL MOTOR CLOCK PROVIDED WITH A SPRING AUTOMATICALLY WOUND Filed Dec. 28, 1956 MQTOR CLOQK PROVIHED WXTH A SPRING AUTQMATICALLY WGUND Ehiro Souobe, Knzuo Ishilrawa, and Yoshi-o Namihi, Tokyo, Japan This invention relates to motor clocks, and more particularly, to the type of clock comprising an escapement mechanism having a balance wheel or a pendulum, a direct current motor for supplying motive power, a spring which is adapted to be wound automatically by a portion of the torque of said motor to store energy, and an additional device such as a time indicator, alarm, musical mechanism and the like which is operated by the stored energy of said spring.

in a clock according to this invention, an escapement mechanism, namely a mechanism comprising a balance wheel or a pendulum, is operated by a direct current motor and at the same time the rotation of the motor is regulated by said escapement mechanism. Furthermore,

a spring is placed between the escapement mechanism and the motor in order to obtain a constant speed continuous rotation of the motor despite voltage fluctuations taking into account the rotational speed of the motor, the inertia moment of the rotor, and the cycle of regulation device.

The hands for indicating time are operated by the motor, continuously rotating at a constant speed as mentioned above, through a gear system and at the same time a spring for the operation of an additional device, such as a time indicating device, alarm, musical mechanism and the like, is automatically wound by the same motor through a clutch spring which makes close contact with a winding shaft until wound to a determined angle which is allowed to slip from the shaft when the winding of the spring through the determined angle has been effected. In these cases, the load imposed on the motor is substantially constant since the load during the winding of the spring and the load during the slip are made sub stantially equal to each other.

When a part of the energy stored in the spring is released and the spring is loosened, the contact between the winding shaft and the clutch spring is again restored to restart the winding operation. The device to be operated by the restored energy of said spring may be a device for time indicating, an alarm, a musical device, and the like.

An object of this invention is to provide a motor clock which has, in addition to a timing mechanism, an additional device such as chimes, an alarm, a musical box or the like which can be operated by the same motor as employed for driving the timing mechanism. According to this invention, an escapement mechanism is driven by a direct current motor and at the same time fan auxiliary spring for time striking or some other operation is wound automatically by a portion of the output of the motor. Since the. clock of this invention can perform such an additional operation without requiring a further motor, the construction of the clock may be made simple and compact so that its cost is minimized.

Another object of this invention is to provide a motor clock which consumes less electric currentucompared with conventional motor clocks. This. can be achieved by driving the motor at a constant speed despite the tent the speed 7 ice presence of an escapement. In a conventional construction, the escapement operates intermittently, but in accordance with this invention a spring is placed between the motor and the cscapement so that the motor rotates at a constant speed and also continuously, thus reducing the consumption of electric current.

A further object of this invention is to provide a motor clock of high accuracy. For this purpose, the load on the automatic Winding system is made substantially constant irrespective of whether the system is being wound or not.

In order to facilitate an understanding of this invention, one of the embodiments of the invention will next be described with reference to the accompanying drawings in which:

Figure l is a perspective view of a clock having-a direct current motor, an escapement mechanism having a balance wheel operated by said motor and a time indieating system provided with a spring arranged to be wound by said motor;

Figure 2 is an enlarged perspective view of the part for automatic winding of the spring of the time indication system of Figure 1;

Figure 3 is a diagram showing the relation between torque and time;

Figure 4 illustrates a time striking mechanism employed in conjunction with the invention; and

Figure 5 is a cross-section through the hour and minute hand spindles.

in the drawings, 1 designates a direct current motor, 2 a gear train, 3 a spring, 4 a connecting lever, 5 a balance wheel system, 6 a second hand, 7 a minute hand, 8 an hour hand, 9 an automatic winding device, 10 a time striking device, 11 a winding shaft (Fig. 2), 12 a clutch spring, 13 a spring seat, 14 a clutch bar, 15 a spring for striking time, 16 a barrel gear, 17 a stop pin (Fig. 2), 18 and 19 pinions, and 2d a gear respectively. As shown, a shaft 21 fixed in a pinion 19 is connected, directly with the minute hand 7. A gear 22 fixed on said shaft 21 is connected with a sleeve '26 mounted loosely on the shaft 21 through the reduction gear trains 23, 24 and 25. The hour hand 8 is fixed on said sleeve 26.

The motive power of the direct current motor 1 drives thebalance wheel system 5 through the gearvtrain 2, the spring 3 and the connecting lever 4 while'the rotation of the motor is controlled by escapement mechanism 5. The motion of the escapement wheel in the escapement mechanism is. intermittent, but the rotation of the motor 1 is made continuous and constant as explained hereafter. -The motor has sufficient power for driving the escapement as well as the timing mechanism, and also for the automatic winding of the spring for the operation or a utilization device such as a time striking device, an alarm and the like. Since the escapement wheel moves intermittently step by step, and the speed at which an impact is applied to a balance wheel is very high, a spring 3 and a connecting lever d are provided between the motor 1 and the escapement wheel so that the spring may give instant impacts to the balance wheel. Fig. 3 illustrates the variation of the torque of the motor 1 (line A) and the resistance moment of the spring 3 (shaded part B) which varies as the intermittent motion of the escapement Wheel proceeds. in the drawing, t is the time when the impact begins and 2 is the time when the impact ceases, and t is the time when the impact starts again. Accordingly t -t is the impact time and i -t is the stop time.

As shown in the drawing, the impact time is very short and the stop timefis long in accordance with the characteristic feature of ,escapement mechanisms as well known, and the motor 1 does not rotate uniformly even if a spring '3 is provided between the motor 1 and the bears on the surface assasse I 7 escapement wheel in a conventional construction, the

angular velocity to; of the rotor at the time 1 being the smallest and the angular velocity m of the rotor at the time t being the largest.

According to this invention, it is contemplated to change the non-uniform rotation of the motor under usual conditions to continuous and constant rotation. Consider that the rotor of the motor 1 is a fly wheel, the spring 3 is a part supplying a resistance moment to the rotor and I is the inertia moment of the rotor, A 'A is the amount of work required, 01 is an average angular velocity of the rotor, and 6 is the rate of the variation of the angular velocity. Then the following formulas may be obtained.

; Accordingly, the velocity of the rotoris determined when the allowable variation rate of the angular velocity,

the inertia moment of the rotor, the required torque of the escapement mechanism and the resistance moment of the spring are all known, and continuous revolution is attained if the conditions mentioned above are satisfied.

The motor rotated continuously at a constant speed by a device as mentioned above drives a timing mechanism comprising a second hand 6, a minute hand 7 and an hour hand 8 through a gear train 2 despite the presence of the escapement mechanism 5.

As illustrated in Fig. 1, a shaft 21 attached to a pinion 19 is connected directly with a minute hand 7. However, an hour hand 8 is connected to a sleeve 26 which is provided at the side surface of a gear 25 and the gear 25 is mounted loosely and rotatably upon the shaft 21.- The gear 25 is actuated through reduction gear trains 24 23, 23, and 22, the gear 22 being connected directly with the shaft 21. The driving shaft 21 is provided at its one end with friction coupling 33 which is engaged with the side surface of the gear 34 in the gear train 2.

An automatic spring winding system generally indicated at 9 in Fig. 1 and shown more in detail in Fig. 2 acts to wind a spring 15 by means of a winding shaft 11 which is driven by a gear 20 in engagement with a pinion 19 of the gear train 2 which is in turn driven by the continuously rotating motor 1. The spring 15 is fixed at one end on a spring seat 13 and is fixed at the other end on a barrel gear 16. Both the seat 13 and the gear 16 are loosely mounted on the shaft 11. The barrel gear 16 is interlocked with the time striking device generally indicated at 10 in Fig. 1 through a gear iflwhich is controlled not to rotate excepting for a time striking operation.

A clutch spring 12 which is wound on the shaft 11 in the same rotating direction as the shaft 11 is fixed at one end on the spring seat 13 and at the other end on a clutch lever 14 which is loosely mounted on the shaft 11. The clutch spring with spring seat 13 and lever 14 have sufiicient friction to be rotated by said shaft until the clutch lever comes into contact with the stop pin.

The clutch spring 12 is wound on the shaft 11 and of the shaft. When the shaft 11 is rotated, one end of the clutch spring 12 fixed on the clutch lever which rotates with the shaft 11 by friction rotates also but the other .end of the clutch spring 12 receives a force from the spring seat 13 which is connected with. the spring 15, and accordingly the clutch spring 12 is wound on the shaft tighter and tighter, and .in such a condition,

the clutch spring 12, the clutch 11 rotate as one body under the 29, and thus the spring for'striking lever 14 and the shaft action of the gear time is wound.

As shown in the drawing, a stop pin 17 is fixed on the barrel gear 16 and, when the clutch lever 14 rotating with the shaft 11 comes into contact with the stop pin g of the spring and the load on the motive clock is substantially prising a gear 17, the lever 14 cannot rotate any further. The shaft continues its rotation, however, since the lever 14 is loosely mounted on the shaft 11 and the clutch spring 12 is loosened by the clutch lever 14 to allow the shaft to slip from the clutch lever 14 and the spring seat 13. Under such a condition, the spring 15 is not wound any further although the shaft 11 continues its rotation. While the shaft 11 slips as described above, there is a load on the shaft 11 but this is only frictional engagement of the clutch spring 12 with the shaft 11 due to the counter ressing action of the spring 15 and there is substantially no difierence in the load compared with the load during the winding operation.

When the time for striking comes and the restraining control of the gear 13 is removed, the barrel gear to is rotated by the energy of the spring 15. For the time striking device, a conventional time striking method can be used. It is to be understood that the winding of the spring can be similarly effected by turning the time indicating hand 7 thereby turning the shaft 11 through the pinion 19 and the gear 26, as in the case when the winding of the spring is effected by the motor while the time indicating mechanism is operated.

When the gear 16 is rotated, the stop pin 17 rotates to come in contact with the other side of the clutch lever 14 and at this moment the unwinding of the spring 15 is stopped. Accordingly, the pressure of the spring 15 can be maintained in a condition of relatively small variation by a winding effected in advance to some extent and also by limiting the angle of winding the spring during the operation within a certain range of angles. The output power can be maintained almost constant and the accuracy of the not affected while efficient time striking can be attained due to the fact that the output of the spring can be maintained almost constant.

A conventional time striking mechanism is shown for an example in Fig. 4. To the shaft 21 of a minute hand 7 is attached a cam disc 27 which is provided with a cut portion 28 at its periphery. A lever 29 is pivotally urged to move towards the cam disc 27 under the tension of a spring 32 connected thereto. Lever 29 is provided with pawls 30 and 31 which are adapted to engage with the cut portion 28 anda fan governor 26 respectively. To the shaft 35 of the fan governor 26 is fixed a pinion 37 with a gear 36 which is mounted securely on a shaft 38 for driving a time striking device 10. The driving power for the time striking device 10 is provided by the transmission mechanism including gear 18, shaft 39, gear train 40, 42, 43, 44 and 38. Therefore, the driving shaft 38 of the time striking device 10 is locked by the lever 29, governor fan 26, shaft 35 and gears 37 and 36 and is normally kept inoperative.

When the minute hand 7 arrives at a predetermined position, however, the pawl 30 of the lever 29 is engaged with the cut portion 28 on the cam disc 27 so as to release the engagement of the pawl 31 with the fan governor 26. Then the time striking device 10 is driven by the power transmission mechanism comprising parts 18, 39, 40, 38, and so forth.

While the above description has been presented with reference to one of the embodiments of this invention as illustrated in the drawings, various variations and modifications may be made without departing from the scope and the spirit of the invention. For example, in the escapement mechanism, a pendulum may be used in place of a balance wheel. It is further to be understood that while the explanations have been made with reference to a motor clock having a time striking device, this invention may also be advantageously applied to a motor clock having other devices, such as an. alarm, 21 musical device or the like.

What is claimed is:

-l. A clock having an energy utilization device comtrain adapted for being driven to indicate 5 time, a shaft driven by said gear train, a clutch spring mounted on said shaft, and a further spring coupled to said clutch spring and Wound thereby, said further spring being coupled to said utilization device for driving the same.

2. A clock as claimed in claim 1 comprising a spring seat loosely mounted on said shaft and supporting said further spring at one end thereof, a gear loosely mounted on said shaft and coupled to the other end of said further spring, and a timing mechanism restricting movement of said gear until the time for operating the utilization device, the clutch spring being a spiral spring coupled to said seat and being driven by said shaft to wind said further spring.

3. A clock as claimed in claim 2 comprising a stop for releasing said clutch spring from said shaft when a predetermined energy level has been achieved in said further spring.

4. A clock as claimed in claim 3 wherein said stop is mounted on said further gear.

5. A clock as claimed in claim 3 comprising a lever loosely mounted on said shaft and coupled to said clutch spring, said lever being engageable by said stop.

References Cited in the file of this patent UNITED STATES PATENTS 987,768 Stadel Mar. 28, 1911 1,530,259 Hall Mar. 17, 1925 1,659,027 Holtz Feb. 14, 1928 1,659,028 Holtz Feb. 14, 1928 1,838,501 Schifi. Dec. 29, 1931 2,546,729 De Millar Mar. 27, 1951 FOREIGN PATENTS 27,178 Great Britain Oct. 1, 1914 384,128 Great Britain Dec. 1, 1932 578,136 Germany June 10, 1933 

